Structural similarities between a membrane-like surface layer on the cell wall of some microbial cells and the lamellar layer of vesicles formed by short-chain phosphonic acids in water. A freeze-fracture study.
A thin layer on the cell wall of some microbial cells, among them such of medical importance (Aspergillus niger, Trichophyton sp.), is characterized by a mosaic-like rodlet pattern in freeze-fracture electron microscopy. A very similar texture could be found in freeze-fractured bilayer vesicles of n-octan phosphonic acid in presence of 50% glycerol. The formation of this structure in phosphonic acid vesicles is connected with the transformation of the bilayer into the solid crystalline state by cooling. The texture could be suppressed by a higher cooling velocity. In absence of glycerol by the normal quick freezing procedure predominantly intermediate stages were fixed. For the interpretation of the structures revealed a model is proposed, where trigonal subunits stick together, because they are hydrophobic on the one side. These subunits are small crystals with a diameter of 4--7 nm. They are in principle also able to construct a bilayer arrangement directly by a "subassembly-selfassembly" mechanism of selforganization. The membrane-like layer on the cell wall of microbial cells may consist of a crystalline bilayer arrangement of similar substances.
D001234:Aspergillus niger / Q000648:ultrastructure*; D002473:Cell Wall / Q000648:ultrastructure; D005614:Freeze Fracturing; D006999:Hypocreales / Q000648:ultrastructure*; D008567:Membranes, Artificial; D063065:Organophosphonates; D013171:Spores, Bacterial / Q000648:ultrastructure; D013172:Spores, Fungal / Q000648:ultrastructure; D013305:Streptomyces griseus / Q000648:ultrastructure*
D008567:Membranes, Artificial; D063065:Organophosphonates